A series of ten discoid medial menisci.

In a retrospective study, 14,731 menisci were examined to determine the incidence of discoid medial and lateral menisci. Of 8040 medial menisci, ten (0.12%) were discoid. Of 6691 lateral menisci, 102 (1.5%) were discoid. Only 22 discoid medial menisci have been reported in the medical literature. The previously reported cases were analyzed as one series and compared with the present series of ten cases as another. The incidence rate of symptoms in patients older than 18 years of age was 62% in the present series and 65% in the other series. The male to female ratio was three to one in both series. In 38% of the patients in this series trauma preceded meniscal symptoms, as compared with 66% in the literature series. Radiographic abnormalities had been reported in two of the patients reported in the literature, but none were noticed in our series. In both series, all patients recovered following meniscectomy, with the exception of one patient in our series, who developed chondromalacia patella from an unrelated patellar abnormality.